Monday, September 19, 2011

Der bestirnte Himmel über mir

I suppose we all have projects or ambitions we are occasionally able to pursue. I've always wished I knew the names of trees, for instance, or the songs of birds.

Living at seven thousand feet in a dry climate and a smaller city I have found myself, more so than at any other time in my life, aware of the presence of the "starry heavens above." I have always wanted to know something of the stars, not necessarily a deep knowledge, but some sense of which constellations are which (beyond the Big Dipper and Orion), and maybe the names of a few stars and other celestial objects.

This summer has not been a good one for viewing. I don't know why, since we've been in a record-setting drought, but the sky has been cloudy almost all summer. The last two nights things cleared up some, and I spotted, for the first time, the well-known galaxy in Andromeda, and the double cluster in Perseus.

Even the most amateur of amateur sky-watchers will perhaps smile at the modesty of these achievements. No matter. Those who, like myself, have gone through most of their lives oblivious to the celestial hemisphere above may find here some motivation to look up.

I have been much helped by four things. The first two are things you look through, a telescope and a pair of binoculars. The telescope is a cheap one--well, mine, very cheap for me, since I won it in a raffle from a local toy store that was going out of business. It retails for around a hundred dollars, so it's not a terribly good scope. But I've seen Jupiter's Medician moons with it, and, looking at Saturn, I have just barely made out a tiny silver ring running round a tiny silver disc.

The binoculars are much more rewarding. It's hard for me to find things with the telescope--the afore-mentioned Andromeda Galaxy took me almost an hour to find, and it had the same "faint-headlight-in-a-fog" appearance as it had in the binoculars.

The other two aids are things one looks at rather than through. A constant companion has been the "Audubon Guide to the Night Sky," with page after page showing typical monthly night skies, constellations (both drawn and photographed), and narratives keyed to the most interesting sights in each. It's invaluable, but, as I used it more and more, I became increasingly aware of its limitation as a two-dimensional representation of a great overhead hemisphere.

Which brings me to the wonders of the celestial globe, a 12-inch sphere illustrating the positions of the stars, constellations, stellar regions, star clusters, deep sky objects, and the annual path of the sun through the zodiac. Upon receiving it I immediately cut from poster board a narrow ring with a slightly less than 12 inch interior diameter which, placed on the globe, works as a "horizon." By orienting Polaris and the Big Dipper I could thereby at any time of the night have a model of the sky above.

The celestial globe has an initially surprising property, that it appears to be a mirror image of the sky. This is, of course, because one is on the outside looking in, rather than (with the real thing) on the inside looking out. It takes some getting used to, but, by imagining that the surface of the globe is being projected outward, one gets adjusted.

The great utility of the celestial globe lies in being able to handle it, to turn it around the celestial pole to get a tactile sense of what most initially puzzled me about those monthly star maps in the Audubon guide: how exactly the (apparent) movement of the celestial sphere caused just those perrenial and seasonal constellations to appear. It also allowed me to visualize, for the first time, through imagining a tiny solar system in the disk of the great circle formed by the zodiac, how and why the sun and the planets remained within the zodiac.